Asphalt is a residue that remains after evaporation of volatile fractions among crude oil components. It is a very complex chemical compound composed mainly of hydrogen and carbon and having bonded thereto small amounts of nitrogen, sulfur and oxygen. It is widely used as a binder for aggregate in the paving of roads on which cars mainly run.
Asphalt is a temperature-susceptible material that changes to a liquid state upon heating and is cured at low temperature. In order to increase the workability of asphalt in road paving, asphalt or aggregate, or both, is used after warming to a predetermined temperature. In the case in which an asphalt composition is transported in divided amounts by trucks or in which the transport distance from an asphalt production plant to a construction site is long or in which the temperature of asphalt decreases with time when being used in construction in a severely cold climate in the winter season, the asphalt concrete composition is cured so as to be difficult to pave, and compaction of the asphalt pavement or the adhesion between aggregate and the asphalt binder is poor so that the quality of the asphalt pavement is poor.
For these reasons, in view of the physical properties of asphalt to soften upon heating and to be cured at low temperature, as well as a variety of paving construction environments such as seasons or transport distances, a sufficient amount of heat should be applied to conventional asphalt to impart softness to the asphalt in order to achieve sufficient workability of the asphalt in paving.
Meanwhile, asphalt pavements sometimes undergo rutting (plastic deformation), which causes serious running problems, along running tracks before 5 years after construction. Alternatively, even though there is no rutting problem, the pavement materials are gradually aged with the passage of time, and eventually undergo severe cracking. For these reasons, asphalt pavements should be regularly repaired. As an example of methods for repairing asphalt pavements, Korean Patent No. 0880030 discloses an asphalt composition for emergency repair of road pavement, which comprises 60-80 wt % of asphalt cement; 15-35 wt % of vegetable oil; and a binder comprising aliphatic polyamides.
Until now, as a method for repair of road and bridge deck pavements, a modified asphalt overlay of grade 2-3 (PG 64-22.76-22) has been generally applied.
However, the asphalt overlay of grade 2-3 has problems in that it has a short life span and insufficient adhesive strength and flexibility, and thus material separation and potholes frequently occur.
Accordingly, in order to minimize the cost of the above-described repair, it is required to develop an asphalt composition which minimizes the rutting of roads paved with the asphalt and which is not aged for a long period of time while not being easily stripped.